Zero- to ultralow-field nuclear magnetic resonance J-spectroscopy with commercial atomic magnetometers

Abstract

Zero-to ultralow-field nuclear magnetic resonance (ZULF NMR) is an alternative spectroscopic method to high-field NMR, in which samples are studied in the absence of a large magnetic field. Unfortunately, there is a large barrier to entry for many groups, because operating the optical magnetometers needed for signal detection requires some expertise in atomic physics and optics. Commercially available magnetometers offer a solution to this problem. Here we describe a simple ZULF NMR configuration employing commercial magnetometers, and demonstrate sufficient functionality to measure samples with nuclear spins prepolarized in a permanent magnet or initialized using parahydrogen. This opens the possibility for other groups to use ZULF NMR, which provides a means to study complex materials without magnetic susceptibility-induced line broadening, and to observe samples through conductive materials.

Chemical Reaction Monitoring Using Zero-Field Nuclear Magnetic Resonance Enables Study of Heterogeneous Samples in Metal Containers

“…A detailed description of the ZULF NMR experimental apparatus is given in Ref. [48]. download file view on ChemRxiv ZULF-RM_SI.pdf (249.41 KiB)…”

“…In this work we study two-step hydrogenation of an unsaturated precursor molecule with para-enriched hydrogen gas using ZULF NMR. This is done by continuously bubbling the hydrogen gas into samples containing dissolved dimethyl acetylenedicarboxylate (DMAD) along with the appropriate catalyst, and observing the NMR signals of the hydrogenation products (dimethyl maleate and dimethyl succinate) over time with a commercial atomic magnetometer [48]. Magnetic shielding and compensating coils are used to create the 'zero-field' region, with residual magnetic-field intensity on the order of 10-100 pT, although the magnetometer can operate in fields up to 50 nT.…”

Zero- to Ultralow-Field NMR Spectroscopy of Small Biomolecules

“…It is based on a commercial spin-exchange relaxation-free magnetometer magnetometer QuSpin-QZFM. 8 The vapor cell is placed approximately 9.5 mm from the sample enclosed in a regular 5 mm NMR tube. The high sensitivity of the magnetometer (about 15 fT/Hz 1/2 ) and a small distance between the cell and the sample are crucial for detection of weak NMR signals under ZULF conditions.…”

“…Moreover, OPM devices are currently available commercially. 8 ZULF NMR employing OPMs is used to distinguish chemicals in the liquid state based on their unique nuclear-spin topology and J couplings, [9][10][11] also allowing characterization of chemically exchanging systems 12 and monitoring chemical reactions. 13 Multidimensional ZULF NMR spectroscopy is also being developed 14 as the methodological portfolio of tools available at zero field continues to grow.…”

Zero-field NMR J-Spectroscopy of Organophosphorus Compounds

“…Atomic magnetometers are often used for this purpose with the main advantages being: low-price, small size and non-cryogenic operation, while ever-growing commercial availability of such sensors leads to technical simplicity and near-zero maintenance. 13,14 While the zero-field J-spectroscopy has been successfully used for thermal studies of isotopically enriched compounds containing 13 C, 15 N nuclei, here we exploit naturally abundant phosphorus-31 ( 31 P) nucleus.…”